MATLAB: Any suggestions on what I have done wrong

debuggingwhile loop

I am attempting to find the smallest number of terms needed in the following series such that the absolute error of P – pi is less than 10^-6.

The series being S = 1/1^2 + 1/2^2 + 1/3^2…………1/n^2.

With P = sqrt(6S)

I have the following code, but have managed to create an infinite loop. Any suggestions as to where I have gone wrong?

S=1;
P=sqrt(6*S);
n=1
while abs(P-pi)>10^(-6)
  n=n+1
  S=S+1/(n^2)
end
disp(n)

Best Answer

The variable P in your loop condition is never being updated in the loop. So if the condition is true at the start of the loop it will always be true - hence the infinite loop

Related Solutions

MATLAB: Problem executing while loop

insert before while n=x;

clc
clear
a = input('number ');
x = input('guess ');
tol = 0.0000001;
n=x
while (abs(n-x)<=tol)
y=(1/a)*x^2;
n = ((x/8)*(15-(y)*(10-3*(y))));
x=n;
end
disp(n)

MATLAB: Help with while loop

You were pretty close, but there are a couple of mistakes.

You start out the error at zero, then ask the loop to run only when the error is greater than 3....
You are not actually calculating the factorial for each new value of n.
You need to use the absolute value when calculating the error.

x=1.5;
y=0;
n=0;
ER=100;  % Don't name a variable 'error'.  Start >3 so loop runs!
while(ER>3)
    f = 1;
    for ii=2:n
      f=f*ii;
    end
    y = y+(x^n/(f));
    ER = (abs(exp(x)-y)/exp(x))*100;
    n=n+1;
  end
  disp(n-1)
  disp(ER)

Best Answer

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MATLAB: Help with while loop

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